The subject matter of the claimed invention pertains to a water soluble fixed copper-borax wood preservative composition and to methods for preparing this wood preservative composition. Borax is the common name for sodium tetraborate decahydrate. Fixed copper compounds are listed in the literature as including copper oxides, copper hydroxide, basic copper carbonate, basic copper sulfate, and copper oxychloride.
As their name implies, fixed copper compounds are water insoluble. To be effective solid wood preservative, fixed copper compounds must be rendered water soluble. This is commonly accomplished by complexing the fixed copper compounds with ammonia or amines. Ammonia and amines add significantly to the health and environmental hazards posed by fixed copper wood preservatives and their elimination will be welcome in the wood preservation industry. Ammonia and amines also encourage the growth of certain wood defacing fungi. These molds require the use of mildewcides when wood is treated during hot, humid weather; and this adds to treating costs.
Borax is a readily available water soluble wood preservative, and it is found in commerce combined with fixed copper compounds which have been made water soluble by adding ammonia or amines. It has not been previously known to use fixed copper compounds combined with borax, wherein the fixed copper compound is not complexed with ammonia or amines, for wood preservation. Borax has limited solubility in water and the commercial product is slow to dissolve. It is believed the limited solubility of borax as well as the difficulty in preparing water soluble complexes of fixed copper compounds and borax has previously hidden their usefulness from those skilled in the art of wood preservation.
Wood preservatives are frequently used in conjunction with water repellents, and these wax emulsions often contain small amounts of ammonia or amines. The levels of ammonia or amines in water repellents are not sufficient to form water soluble fixed copper complexes in fixed copper treating solutions.
Wood preservatives for use in waferboard need not be completely water soluble. Fixed copper compounds used in waferboard preservation do show increased protection where at least some of the fixed copper compound is water soluble. Small amounts of water insoluble fixed copper compounds are not objectionable in solid wood preservatives so long as their particle size is small enough to penetrate the wood.